The present invention relates to a method and apparatus for conveying containers along a conveyor line and for combining the containers into a single file orientation. More particularly, the present invention is directed to a series of interrelated conveyor sections that are tilted such that as randomly oriented containers are fed along the conveyors, they are caused to combine in a pressureless fashion into a single file orientation along a guide rail while at the same time accelerating in conveyor speed and maintaining their stability.
Oftentimes in bottle or container handling processes, it is important to arrange the containers or bottles from a random grouping to a single-file for processing. For example, when filling containers, it may be important for timing purposes that the containers be in single file for the filling process. Alternatively, during inspection processes, especially optical inspection processes it is advantageous that the containers be in single file to ensure non-interference. When manufacturing process speeds are high, for example greater than about 150 feet per minute, it is often difficult to arrange a random grouping of containers without knocking many of the containers over. This is particularly acute with lighter containers, plastic containers or petaloid-based shaped bottles.
Generally, single filing of a wide stream of containers takes place through the aid of converging rails simultaneously with the containers being transferred to conveyors of sequentially greater speed. This is known as "pressure combining." In such conventional container single filers, blocking, jamming or bridge formations are frequent due to the bottle-bottle pressure involved. In such conventional container single filers, mechanical aids, such as horizontally working vibrators and exocentric-controlled rail movements are therefore used or measures are taken in order to reduce the risk of jamming. The drawbacks of the conventional container pressure combiners increase with increasing capacity and may include:
1. poor operational reliability due to jams and the creation of fallen containers, and PA1 2. generation of wear rings and damage on the containers because of wedge effects.
There are many known techniques and apparatus for aligning randomly oriented containers on a conveyor into single file. U.S. Pat. No. 5,170,879 describes a conveyor system where a plurality of randomly oriented containers are fed at an angle to a conveyor belt dimensioned to convey a single line of the containers. As the containers are fed along the input conveyor, they are forced up against a step shaped guide rail which funnels the containers down to the single file conveyor belt. The single file conveyor belt has holes therein and a vacuum is drawn therethrough to ensure that the containers remain in an upright position. However, during random feeding, the containers are subject to a great deal of impact. At high output speeds, this impact could cause considerable damage to the containers and cause a high number of the containers to be knocked over.
U.S. Pat. No. 4,544,059 describes a conveyor apparatus wherein a random group of containers is fed from one conveyor to another and is re-oriented into a single file. This re-orientation is accomplished through a rotary mechanism and a series of arms which realign the mass group of containers. Again, however, at high speeds the arms may damage the containers or cause them to fall.
Another problem with both of the above-noted apparatus is the complexity and number of parts required. Such a complex device is expensive and subject to frequent downtime due to failure.
Another method and apparatus for forming a single file line of containers on a conveyor is described in U.S. Pat. Nos. 4,489,820 and 5,147,023. These patents teach the use of an at least partially tilted conveyor belt using the effects of gravity to align containers along a guide rail in a single file. An apparatus is disclosed in these patents wherein the end section of the feed conveyor laterally adjacent the intermediate conveyor and the section of the downstream conveyor succeeding the intermediate conveyor are inclined in the same manner as the intermediate conveyor and at such an angle that the resulting declivity drift causes the bottles to slide downwards over the laterally adjacent conveyor portions of the intermediate conveyor, the lowermost side of the feed conveyor being provided with a support railing connected adjacent the intermediate conveyor to the guide surface, the latter being formed as a support surface supporting the bottles at the lower side of the intermediate conveyor.
The apparatus disclosed in U.S. Pat. No. 4,489,820 and 5,147,023, although eliminating some of the problems of the aforementioned apparatus, still suffer from other problems. These apparatus rely on the effects of gravity to ensure that the containers slide downwardly into other containers already aligned on a guide rail. The downward slide of containers causes momentum to build. At high output speeds, that momentum coupled with forward movement, causes instability in the container and thus results in a high number of containers falling over. This is particularly acute with lighter PET and plastic containers which inherently exhibit instability.
What is desired is a combining conveyor system that is capable of outputting a high rate, with chain speeds in excess of 150 feet per minute, in a single file with minimum tip overs.
An object of the invention is to solve the above mentioned disadvantages and therefore to provide an improved combining conveyor for conveying containers while forming a single file orientation. To achieve these and other objects, the present invention is directed to a pressureless combiner conveyor having at least two conveyor sections adjacent to one another, one of which is angled upwardly and angled with respect to the combiner guide rail. The invention includes an input conveyor to supply a plurality of containers having no specific orientation, and an input guide rail to guide moving containers to one side of the input conveyor. Positioned adjacent to the input conveyor section is a combining conveyor section with a substantially linear guide rail, the combining conveyor section being tilted at a predetermined angle along the axis of the guide rail. An output conveyor section is aligned adjacent to the combining conveyor sections for outputting a single-file line of containers and an ejector may be positioned along the output conveyor section to eject fallen containers on the output conveyor.
The guide rail comprises a low-friction material which contacts the lower portion of the containers and provides support for the higher portion of the containers should they impact the rail and start to lean.
According to one aspect of the present invention the tilt angle of the combining conveyor is in a range of from about one-half inch to about one inch per foot of width of the combining conveyor.
According to another aspect of the invention, the combining conveyor includes a plurality of conveyor chains, wherein the conveyor chain closest to the input conveyor runs at a slower speed than the conveyor chain farthest from the input conveyor.
According to still another aspect of the invention the combining guide rail section predetermined angle is a function of one or more of the following variables: container dimensions and stability characteristics, conveyor speed, conveyor tilt angle, rail/bottle contact points, but is generally kept to as small an angle as possible to keep container to rail collisions as inelastic as possible.
According to yet another important aspect of the invention, the combining guide rail is arranged such that it contacts only the lower portion of a container. If the container tips toward the guide rail, then it contacts the upper portion of the guide rail at or near the center of gravity of the container, thereby being stabilized.
The present invention also includes a method for simultaneously conveying and combining a plurality of containers into single file. The method includes feeding a plurality of randomly oriented containers onto an input conveyor and guiding the randomly oriented containers to an edge of the input conveyor and onto an adjacent edge of a combining conveyor. The method further contemplates tilting the combining conveyor by a predetermined angle such that the edge adjacent the input conveyor is lower than the opposite edge of the combining conveyor. The method further includes driving the combining conveyor(s) at increasingly faster speeds than the input conveyor so as to accelerate the containers as they are fed onto and across the combining conveyor. The method further contemplates guiding the containers along the combining conveyor by a guide rail extending across the combining conveyor at an angle determined at least in part by the tilt angle and combining conveyor speed such that containers become aligned in a single file along the guide rail as they are conveyed along the combining conveyor, and outputting a single file line of containers on an output conveyor having an edge aligned adjacent to the combining conveyor.
In another aspect, the present invention provides a method for maintaining the stability of the containers. This is done by providing lower and upper container supports on the guide rail. As a result, if a container contacts the lower container support, it pivots about that point of contact. The momentum causes the container to lean into the upper container support, with the center of gravity of the container remaining within its stability region. The reaction from hitting the upper container support causes the container to pivot back.
The apparatus and method according to the present invention ensures that at output conveyor speeds of greater than 150 feet per minute, a single file orientation of containers can be achieved with a minimum number of fallen containers. The tilted combining conveyor section(s) provides a more stable position for the containers and allows for single filing at slower conveyor speeds, thus discouraging containers from falling. The rail angle and rail/container contact points minimize fallen containers by buffering container/rail collisions.
Other than in the operating examples, or where otherwise indicated, all numbers expressing angles, speeds, or other operating conditions used herein are to be understood as modified in all instances by the term "about".
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.